Comment 4 for bug 1618956

Ya, this broke with the update to 2.12.4, and works if you downgrade to 2.12.3

You can apply this

=== modified file 'ubiquity/frontend/gtk_ui.py'
--- ubiquity/frontend/gtk_ui.py 2016-06-30 14:33:11 +0000
+++ ubiquity/frontend/gtk_ui.py 2016-09-02 08:39:34 +0000
@@ -759,6 +759,9 @@
         self.set_current_page(0)
         self.live_installer.show()

+ self.start_slideshow()
+ Gtk.main()
+
         while(self.pagesindex < len(self.pages)):
             if self.current_page is None:
                 return self.returncode
@@ -814,8 +817,6 @@

         # There's still work to do (postinstall). Let's keep the user
         # entertained.
- self.start_slideshow()
- Gtk.main()
         self.pending_quits = max(0, self.pending_quits - 1)
         # postinstall will exit here by calling Gtk.main_quit in
         # find_next_step.

to test just the slideshow step.